Temporal variation in synchrony among chinook salmon (Oncorhynchus tshawytscha) redd counts from a wilderness area in central Idaho

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 60; no. 7; pp. 840 - 848
• Main Authors: Isaak, Daniel J, Thurow, Russell F, Rieman, Bruce E, Dunham, Jason B
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.07.2003; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Animal populations; Animal, plant and microbial ecology; Anthropogenic factors; Applied ecology; Aquatic birds; Biological and medical sciences; Creeks; Distribution; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fish populations; Fish stocking; Freshwater; Fundamental and applied biological sciences. Psychology; Gravel; Habitats; Life history; Marine biology; Metapopulations; Oncorhynchus tshawytscha; Population decline; Population levels; Rivers; Salmon; Spawning; Spring; Streams; Summer; Wilderness; Wilderness areas; United States; North America; Idaho; America; United States > US; USA, Idaho, Salmon R; USA, Idaho; Salmonidae; Metapopulation; Oncorhynchus tshawytscha; Drainage patterns; Synchronization; Population decline; Breeding site; Interannual variation; Freshwater environment; Vertebrata; Population survey; Pisces; Models; Stock; Ecological abundance
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f03-073

Metapopulation dynamics have emerged as a key consideration in conservation planning for salmonid fishes. Implicit to many models of spatially structured populations is a degree of synchrony, or correlation, among populations. We used a spatially and temporally extensive database of chinook salmon (Oncorhynchus tshawytscha) redd counts from a wilderness area in central Idaho to examine patterns in synchrony as these fish underwent a sixfold decrease in abundance. Our results suggested that populations became strongly synchronous as abundances decreased and that the range, or diversity of correlations, exhibited among populations also decreased. These changes indicate that the likelihood of simultaneous extirpations has increased, which could have long-term detrimental consequences for metapopulation persistence. Implications for management are that the resilience of many metapopulations to large-scale disturbance and anthropogenic suppression may not depend solely on attempts to maintain large and productive component populations, but also on efforts to desynchronize populations that have become strongly correlated. Such efforts could entail promoting the existence of a broad distribution and diversity of habitats that support a wide array of life-history forms and ensuring that some habitats are sufficiently spatially disjunct so that risks from catastrophic stochastic events are minimized.